Direct attach footwear construction

ABSTRACT

A shoe construction having an outsole direct attached to a midsole with a mechanical interlock. The outsole includes a bottom and a wall extends upwardly therefrom, optionally around the entire periphery of the outsole. At a pre-selected distance above the bottom, a rib or a plurality of protrusions extend inwardly from the wall so that a void is defined between the protrusions and the bottom. The midsole is direct attached to the upper, the bottom, the wall and the protrusions. The protrusions enhance the mechanical securement of the midsole to the outsole. To assemble the construction, the outsole and the upper are positioned in a mold a pre-selected distance apart to form a cavity. A plastic material is injected into the cavity and direct attaches to the outsole and upper. As the plastic material fills the cavity, it seeps into the void defined between the projections and the upper surface.

BACKGROUND

[0001] The present invention relates to a footwear construction, andmore particularly to a footwear construction including a direct attachoutsole.

[0002] The footwear industry has developed many shoe constructions thatare both durable and aesthetically pleasing. One such sole constructionis referred to as the welt construction. There are a variety of popularwelt constructions, however, in each, a “welt,” for example, a strip ofmaterial such as leather or rubber, connects an upper to an outsole toform the footwear. The welt generally includes a horizontal base fromwhich upward and downward ribs extend. The upwardly extending rib isstitched to the upper and the downwardly extending rib or the base isstitched to the sole to hold the upper and outsole together. The weltitself is semi-rigid or hard to withstand the forces exerted through thestitching. In the finished shoe, the welt provides an aestheticallypleasing transition between the sole and upper.

[0003] Although the welt construction is durable and aestheticallypleasing, the welt and associated stitching compromises the flexibilityof the shoe. This is true even in welt constructions where the sole is ahollow shell filled with a flexible polyurethane foam material.Furthermore, the inclusion of the welt in welt construction footwearincreases the cost of and the time required to manufacture suchfootwear.

[0004] In an effort to improve the flexibility of footwear, several soleconstructions have been developed that direct attach the sole to theupper with a midsole. These constructions are significantly differentfrom and unrelated to welt constructions because they eliminate a needfor a welt altogether and rely on a very different construction to holdthe upper and sole together. As shown in FIG. 1, a typical direct attachconstruction 100 includes a wearing sole 110 direct attached to aflexible polyurethane midsole 120, which is in turn direct attached toan upper 130. The wearing sole includes a flat, featureless surface 112to which the polyurethane midsole is secured via gluing or by moldingthe polyurethane over the surface 112 during manufacture of the shoe.Although this direct attach construction is flexible and resilient, itis not sufficiently durable because the wearing sole 110 is prone todetach from the midsole 120, particularly in the toe region as shown inFIG. 2. In some cases, the sole detaches completely from the midsolewhich can cause injury to the wearer, especially if he or she is engagedin strenuous activity.

SUMMARY OF THE INVENTION

[0005] The aforementioned problems are overcome in the present inventionwherein a direct attach construction is provided that includes anoutsole direct attached to a midsole with a mechanical interlock. Theoutsole includes one or more protrusions extending inwardly from a wallextending around the periphery of the outsole. These protrusions aresurrounded by and/or encapsulated by the plastic material from which themidsole is constructed to create the mechanical interlock.

[0006] In a preferred embodiment, the midsole is constructed from aplastic material, for example polyurethane, which encapsulates andintersecures to the multiple protrusions to increase the mechanicalstrength of the direct attach bond between the outsole and the midsole.

[0007] In a more preferred embodiment, the outsole includes an uppersurface and a tread pattern opposite therefrom. The upper surface isbounded by the peripheral wall and located below the protrusions apre-selected distance to define a void. The plastic material of themidsole seeps into the void and around the protrusions to fullyencapsulate the protrusions.

[0008] In an even more preferred embodiment, a portion of the treadpattern is reflected through to the upper surface of the outsole toincrease the surface area thereof and further increase the strength ofthe direct attach bond between the outsole and the midsole.

[0009] The present invention also provides a method for manufacturingfootwear including the steps of: (a) providing an outsole including awall extending around the periphery of the outsole and one or moreprotrusions extending inwardly toward the center of the outsole from theperipheral wall; (b) positioning an upper a pre-selected distance abovethe outsole; (c) positioning a mold adjacent the upper and theperipheral wall to define a midsole cavity; and (d) introducing plasticmaterial into the cavity to form the midsole of the shoe and directattach the midsole to both the outsole and the upper, wherein themolding material encapsulates the protrusions of a outsole to provide amechanical interlock between the midsole and outsole.

[0010] The present invention provides a durable and comfortable soleconstruction. Because the present invention direct attaches an outsoleto an upper, rather than securing the outsole to the upper with a welt,the construction is very flexible and resilient. The use of a plasticmaterial, such as polyurethane, to direct attach the outsole to theupper also makes the outsole lighter than welt constructions.Additionally, the mechanical interlocking of the midsole to the outsoleenhances the strength of the direct attach bond between the midsole tothe outsole. This interlock prevents delamination of the outsole fromthe midsole, making the construction very durable.

[0011] These and other objects, advantages and features of the inventionwill be more readily understood and appreciated by reference to thedetailed description of the invention and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 is a sectional view of a direct attach sole constructionaccording to the prior art;

[0013]FIG. 2 is a perspective view of a delaminated direct attach soleconstruction according to the prior art;

[0014]FIG. 3 is a sectional view of an article of footwear incorporatingthe sole construction of the present invention;

[0015]FIG. 4 is an exploded perspective view of the article of footwear;

[0016]FIG. 5 is a top perspective view of an outsole of the presentinvention; and

[0017]FIG. 6 is a sectional view of the article of footwear in a moldingoperation.

DETAILED DESCRIPTION OF THE INVENTION

[0018] A boot constructed in accordance with a preferred embodiment ofthe present invention is shown in FIGS. 3 and 4, and generallydesignated 10. For purposes of disclosure, the present invention isdescribed in connection with a three-quarter height boot, however, thepresent invention is well-suited for use with other types of soled,un-welted footwear.

[0019] In general, the boot 10 includes an outsole 20 that is directattached to a midsole 40, which is direct attached to an upper 50. Asbest shown in FIG. 5, the outsole 20 includes a peripheral wall 22, fromwhich one or more protrusions 24 extend inwardly formed the center ofthe outsole. The midsole material 40 surrounds the protrusion 24 (FIG.3) to mechanically interlock the outsole 20 and midsole 40.

[0020] The upper 50 is generally conventional and will not be describedin detail. Suffice it to say that the upper 50 includes a quarter 52, avamp 54, and a backstay 56. The upper 50 terminates in a lowerperipheral edge 58 that is direct attached to the midsole 40 asdescribed in detail below. The upper 50 is preferably manufactured fromleather, canvas, nylon or other suitable materials, and may include aliner (not shown) or other conventional accessories.

[0021] The outsole 20 is manufactured from a relatively hard rubber orother sufficiently durable and wear-resistant material. The bottom 26includes an upper surface 32 and an outer surface 34. The outer surface34 forms the wearing surface of the outsole 20 and is contoured todefine the desired heel and tread pattern. The outer surface 34 may betextured to improve the traction and aesthetic appeal of the boot.Optionally, the upper surface 32 may be textured. The tread pattern ofthe outer surface 34 may reflect through the bottom 26 so that recessescorresponding to portions of the tread pattern are defined in the uppersurface 32. If desired, the outsole 20 may also include a shank (notshown), a filler (not shown) or other conventional sole components.

[0022] The outsole 20 also includes a peripheral wall 22 extendingupwardly from the periphery of the bottom 26. The peripheral wall 22includes an interior 23 and an exterior 25. The exterior 25 of theperipheral wall 22 may be contoured or textured to provide the desiredvisual appearance of the outsole of the interior 23 may also be texturedas desired. The peripheral wall 22 further includes multiple protrusions24 extending inwardly near the upper edge of the interior 23 of theperipheral wall 22. As shown, the protrusions 24 are circular sections,however other shapes may be substituted as desired. The protrusion(s)also may collectively form a rib, with or without indentations, asdesired. As used herein, protrusion may also include a rib. Theprotrusions are separated from the upper surface 32 a pre-selecteddistance 23 to cooperatively define a void between the protrusions andthe upper surface. The material protrusions 24 interlock with themidsole material 24 to improve the mechanical interconnection of themidsole and outsole. Optionally, the protrusions 24 define apertures(not shown) through which the midsole 40 extends to further improve theinterconnection of the outsole and midsole.

[0023] The midsole 40 preferably is constructed from a resilient andflexible polyurethane. The uppermost portion of the midsole is directattached to the peripheral edge 58 of the upper, and optionally anyinsole 60 included in the boot. The midsole 40 preferably includes anexterior wall 42 that may be textured to provide a desired appearance orfunction in the completed boot. Optionally, the midsole exterior wall 42and wall exterior 25 co-terminate together on the outside of the shoe.

[0024] The lowermost portion of the midsole define a peripheral groove44. This peripheral groove conforms to the protrusions 24, and where themidsole 40 is direct attached to the outsole 20, the portion of themidsole in the peripheral groove substantially encapsulates thesurrounds the protrusions 24. Below the groove 44, the midsole includesa base 46, which itself is direct attached to the upper surface 32 ofthe outsole. Preferably, the base intrudes or seeps into the voiddefined between the protrusions 24 and the upper surface 32 tosubstantially occupy or fill that void. Where the upper surface of thesole 20 includes recesses 28 reflected therein, the midsole 40substantially fills those recesses as well.

[0025] In the depicted boot 10, the midsole is polyurethane.Polyurethane is generally well-known in the footwear industry, andtherefore will not be described in detail. The rigidity and flexibilityof the polyurethane can be varied from application to application, asdesired, using a variety of well-known techniques, such as by adjustingthe type and proportionate amount of the reactants that make up thematerial. In addition, the rigidity and flexibility of the polyurethanecan be varied by adjusting the volume of polyurethane used. Although thepolyurethane is the preferred midsole material, the density and precisechemical make-up of the midsole material may vary depending on a varietyof factors, including the size of void defined between the protrusions24 and the upper surface 32, or the recesses 28 and the desiredcushioning and flexibility characteristics of the boot.

Manufacture and Assembly

[0026] The boot 10 is manufactured using direct attach machinery. Inparticular, the upper 50 is manufactured using generally conventionaltechniques and apparatus. The desired upper material (not shown) is cutto form the various elements of the upper, including the quarter 52,vamp 54 and backstay 56. The elements of the upper 50 are then fittedand sewn together. A lining (not shown) may be sewn within the upperduring the fitting step. The fitted upper 50 is stretched over a last(not shown) and stapled to insole 60, preferably along the lowerperipheral edge 58 of the upper 50 using conventional apparatus andtechniques to intersecure the upper 50 and insole 60. Alternatively,insole 60 can be sewn or glued to the upper 50 in a conventional manner.

[0027] The outsole 20 is preferably injection or pour molded from ahard, durable rubber using conventional molding apparatus. The outsole20 may be manufactured from other durable outsole materials. Theprotrusions 24, upper surface 32 and desired tread pattern in the outersurface 34 are all formed during the molding operation as an integralpart of the outsole 20.

[0028] With the outsole 20 manufactured, it is direct attached to themidsole and upper as shown in FIG. 6. The machinery to perform thedirect attachment preferably includes a die 80 that includes a top half82 which receives the upper, and a bottom half 84 which receives theoutsole 20. Optionally, the outsole 20 may include tabs 27 which aregripped by the die halves to better hold the outsole in place. The diehalves are designed so they close to hold the upper in appropriatealignment with and a pre-selected distance above the outsole 20. The diehalves upper and outsole also form the cavity 41 in which the midsole isformed.

[0029] With the outsole 20 and the upper inserted into the appropriatedie halves, the appropriate volume of material to form the midsole 40 isinjected through ports 86 into cavity 41. Preferably, the mold holds theupper 50 and outsole 20 firmly enough to prevent injected material fromexiting the mold. As the material is injected into the void 41, itsubstantially surrounds, entraps, interlocks and direct attaches to thevarious components of the upper 50 and outsole 20. In particular, thematerial seeps into the void defined between the protrusions 24 and theupper surface 32, and substantially encapsulates the protrusions to formthe mechanical interlock between the outsole and midsole in the finishedboot. The material continues to be injected until enough is present inthe cavity 41 to direct attach to both the upper 50 and the componentsof the outsole 20. Optionally, the material may be poured into thecavity above the outsole and the upper placed over the cavityimmediately after pouring.

[0030] After the midsole material 40 is sufficiently cured to directattach the midsole 40 to the upper 50 and outsole 20, the boot may beremoved from the die 80.

[0031] A number of conventional finishing operations are performed onthe boot 10. For example, the edges of the midsole 40 and outsole 20 aretrimmed and shaped, with the tab 27 preferably being removed; the upper50 is cleaned, polished, and treated as appropriate and necessary; andthe laces are inserted in the eyelets.

[0032] The above descriptions are those of the preferred embodiments ofthe invention. Various alterations and changes can be made withoutdeparting from the spirit and broader aspects of the invention asdefined in the appended claims, which are to be interpreted inaccordance with the principles of patent law including the doctrine ofequivalents. Any references to claim elements in the singular, forexample, using the articles “a,” “an,” “the,” or “said,” is not to beconstrued as limiting the element to the singular.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. An article of footwearcomprising: an upper including a lower peripheral edge; an outsoleincluding a wearing surface, an upper surface opposite the wearingsurface, a peripheral wall extending upwardly around at least a portionof the upper surface, said peripheral wall including at least oneprotrusion extending inwardly from said peripheral wall and disposedabove said upper surface a first pre-selected distance; and a materialdirect attached to said lower peripheral edge and said outsole so thatsaid lower peripheral wall and the outsole are joined substantially onlyby direct attachment of the material to both the lower peripheral walland the outsole.
 2. The article of footwear of claim 1 wherein saidoutsole is disposed substantially entirely below said lower peripheraledge a second pre-selected distance.
 3. The article of footwear of claim1 wherein the peripheral wall includes a terminating end, said lowerperipheral edge disposed a second pre-selected distance above theterminating end.
 4. The article of footwear of claim 1 wherein thewearing surface includes a tread, and a portion of the tread isreflected in the upper surface.
 5. The article of footwear of claim 1wherein the upper surface is textured to increase the surface areathereof.
 6. The article of footwear of claim 5 wherein at least aportion of the upper surface conforms to the tread so that at least onerecess is formed in the upper surface and wherein the materialsubstantially fills the at least one recess.
 7. The article of footwearof claim 1 wherein the protrusions are circular sections and aresubstantially encapsulated by the material.
 8. The article of footwearof claim 7 wherein the material is polyurethane.
 9. A footwearconstruction comprising: an upper; a midsole direct attached to saidupper, said midsole including a base and defining a peripheral groove;and an outsole including a wearing surface and an upper surface oppositesaid wearing surface, said outsole including a periphery bounded atleast partially by a wall, said wall including a wall interior and atleast one protrusion extending inwardly from said wall interior, saidprotrusion direct attached to said midsole within said peripheral grooveto form a mechanical interlock between the outsole and said midsole,said outsole secured to the upper substantially only by directattachment of the upper to the midsole and direct attachment of themidsole to the outsole.
 10. The footwear construction of claim 9 whereinsaid wall exterior is viewable by a wearer.
 11. The footwearconstruction of claim 9 wherein said at least one protrusion is a rib,and wherein the peripheral groove conforms to said rib and said midsoleencapsulates said rib.
 12. The footwear construction of claim 9 whereinsaid at least one protrusion extends substantially around the periphery.13. The footwear construction of claim 12 wherein said at least oneprotrusion is of a circular section shape.
 14. The footwear constructionof claim 9 wherein the midsole includes a midsole exterior.
 15. Thefootwear construction of claim 14 wherein the wall exterior and themidsole exterior are both viewable by a user.
 16. The footwearconstruction of claim 14 wherein said midsole exterior co-terminateswith said wall exterior.
 17. A method for constructing an article offootwear comprising: providing an upper; providing an outsole includinga bottom and a wall extending upwardly from the bottom and including aninwardly extending protrusion separated from the bottom a pre-selecteddistance to form a void; positioning the outsole and upper in a mold;introducing a material into the mold between the outsole and the upperso that the outsole and upper are secured together substantially only bythe direct attachment of the material to both, wherein the materialsubstantially fills the void and substantially encapsulates theprotrusion.
 18. The method of claim 17 wherein the bottom includes anupper surface and a tread, and wherein the tread is reflected in theupper surface to define a plurality of recesses.
 19. The method of claim18 wherein the material substantially fills the recesses in saidintroducing step.
 20. The method of claim 19 wherein the encapsulationof the protrusion forms a mechanical interlock between the material andthe outsole when the material cures.